RESEARCH ARTICLE Open Access

Surgical management of urolithiasis – asystematic analysis of available guidelinesValentin Zumstein1,2*†, Patrick Betschart1†, Dominik Abt1, Hans-Peter Schmid1, Cedric Michael Panje3

and Paul Martin Putora3,4

Abstract

Background: Several societies around the world issue guidelines incorporating the latest evidence. However, even themost commonly cited guidelines of the European Association of Urology (EAU) and the American Urological Association(AUA) leave the clinician with several treatment options and differ on specific points. We aimed to identify discrepanciesand areas of consensus between guidelines to give novel insights into areas where low consensus between the guidelinepanels exists, and therefore where more evidence might increase consensus.

Methods: The webpages of the 61 members of the Societé Internationale d’Urologie were analysed to identify all listedor linked guidelines. Decision trees for the surgical management of urolithiasis were derived, and a comparative analysiswas performed to determine consensus and discrepancies.

Results: Five national and one international guideline (EAU) on surgical stone treatment were available for analysis. While7 national urological societies refer to the AUA guidelines and 11 to the EAU guidelines, 43 neither publish theirown guidelines nor refer to others. Comparative analysis revealed a high degree of consensus for most renal andureteral stone scenarios. Nevertheless, we also identified a variety of discrepancies between the different guidelines, thelargest being the approach to the treatment of proximal ureteral calculi and larger renal calculi.

Conclusions: Six guidelines with recommendations for the surgical treatment of urolithiasis to support urologists indecision-making were available for inclusion in our analysis. While there is a high grade of consensus for most stonescenarios, we also detected some discrepancies between different guidelines. These are, however, controversialsituations where adequate evidence to assist with decision-making has yet to be elicited by further research.

Keywords: Consensus, Guidelines, Urolithiasis, Management, Surgical, Decision tree

BackgroundA range of procedures is in use for the surgical treat-ment of urolithiasis. Treatment strategies are mainlybased on stone location and size, and the patient’scomorbidities and preferences. Guidelines have beendeveloped to support clinicians in selecting the mostappropriate treatment in controversial situations. Severalinstitutions around the world have issued guidelinesincorporating the latest evidence.However, even the most commonly cited guidelines of

the European Association of Urology (EAU) and the

American Urological Association (AUA) leave theclinician with several treatment options and differ onspecific points, such as cut-off values for stone size andrecommendations for the treatment of choice [1–3].Ambiguities and discrepancies between different guide-lines may result from different interpretations of theevidence available and possible methodological differ-ences in guideline creation. Therefore, careful analysis ofthe similarities and differences between different sourcescan provide additional insight [4].We aimed to determine how many guidelines on

the surgical management of urolithiasis actually existand the urological associations that recommendedthem. We systematically analysed the criteria pro-posed for decision-making and the recommended sur-gical approaches in each guideline. In addition, we

* Correspondence: valentin.zumstein@gmail.com†Equal contributors1Department of Urology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland2Department of Urology, University Medical Center Hamburg-Eppendorf,Hamburg, GermanyFull list of author information is available at the end of the article

© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Zumstein et al. BMC Urology (2018) 18:25 https://doi.org/10.1186/s12894-018-0332-9

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aimed to identify discrepancies and areas of consensusbetween guidelines, with particular attention to the twomajor guidelines, those of the EAU and AUA.This work provides a systematic analysis of the

recommended surgical management of urolithiasisworldwide, and gives novel insights into areas wherelow consensus between the guideline panels exists,and therefore where more evidence might increaseconsensus.

MethodsGuidelines were selected using the membership listof the Societé Internationale d’Urologie (SIU) (http://www.siu-urology.org/society/national-delegates). Thewebpages of all 61 members that are represented bydelegates were analysed for mentions of and links toguidelines for the surgical management of renal andureteral calculi.Two authors (V.Z., P.B.) independently assessed all

guidelines, and decision trees for the surgical manage-ment of urolithiasis were derived, followed by cross-checking and clarification of any differences by a thirdauthor (D.A.). The methodology of this approach hasbeen recently described [5] and was successfully usedin different fields including radiotherapy in prostatecancer [6], expert opinions of the systemic treatmentof recurrent glioblastoma [7], renal cell carcinoma [8, 9]and sarcoma [10]. In cases where first-, second- and oreven third-line recommendations were provided, alltreatment options were included into the decisiontrees regardless of their hierarchical level. Althoughhierarchical levels were assessed, they were not incor-porated into the decision trees. Decision trees werebuilt based on the criteria used in the guidelines ana-lysed. These were stone location, i.e. renal non-lowerpole, renal lower pole, and proximal and distal ureter;and stone size, i.e. > 20 mm, 10–20 mm, < 10 mm forrenal stones, and > 10 mm or < 10 mm for ureteralstones [1, 2]. All treatment modalities mentioned inthe different guidelines were included in our analyses:shock wave lithotripsy (SWL), percutaneous nephro-lithotomy (PNL/PCNL), ureterorenoscopy includingflexible and semi-rigid URS, covering also the termsretrograde intrarenal surgery (RIRS) and cirurgiaintrarenal retrograda (CIRR) as described in the EAUand Sociedad Argentina de Urologia (SAU) guidelines[2, 11, 12], and open surgery. Patient preference andcontraindications were considered to be universalfactors and were therefore omitted from the analysis.Moreover, recommendations on conservative treatment,special cases (e.g. stone management in pregnancy, stag-horn stones, cysteine stones) and postoperative follow-upwere not part of our systematic analysis.

All decision trees were analysed and compared toeach other to determine consensus or discrepanciesbetween each possible combination of parameters usingweb-based software (Diagnostic Nodes), as describedpreviously [5–7, 13].To evaluate discrepancies, a combined tree containing

all recommendations was generated. A mode tree wasalso generated to identify the most common combin-ation of recommendations for each possible situation.Consensus was defined as complete overlap between

the recommended treatments for any case. If all guide-lines recommended only one therapy for a specificsituation, agreement was 100%. However, if three ofsix guidelines recommended therapy A only, and theothers therapy A or B, this resulted in only 50% agree-ment for therapy A.In addition to comparing all guidelines, the two inter-

national and most frequently cited guidelines issued bythe EAU and AUA were separately compared to high-light discrepancies or areas of consensus.

ResultsAnalysis of the websites of the 61 member associationsrepresented by delegates of the SIU showed 6 nationalguidelines: AUA – American Urological Association[1, 3], SAU – Sociedad Argentina de Urologia [11, 12];AFU – French Association of Urology [14]; DGU –German Society for Urology [15]; and SUA – SingaporeUrological Association [16]; and the international guidelinesfrom the EAU [2]. Some national guidelines (e.g. guidelineof the Japanese Urology Association) were not includedinto the analysis due to linguistic difficulties caused by fontsystems or scripts. Eleven national urological societies referwebsite users to the EAU guidelines or the AUA guide-lines (5 to both the EAU and AUA), 43 did not publishtheir own guidelines or refer readers to any others(Table 1).Decision trees were able to be derived from all guide-

lines identified. The site of the stone is classified consist-ently, i.e. proximal or distal ureteral, and lower pole ornon-lower pole renal calculi, in all guidelines, except theAFU guidelines, which do not explicitly classify lowerpole renal stones as an entity in their own right.While most guidelines distinguish between > 10 mm

and < 10 mm for ureteral stones, stone size is not specif-ically mentioned for distal ureteral calculi in the DGUrecommendations or for proximal ureteral calculi in theAFU guidelines.With regard to renal stone size, thresholds of < 10 mm,

10–20 mm and > 20 mm are used in the EAU, DGU andSAU guidelines, whilst the AUA guidelines differentiatebetween lower pole calculi > 10 mm and ≤ 10 mm, andnon-lower pole stones > 20 mm and ≤ 20 mm. The SUAguidelines provide recommendations for lower pole calculi

Zumstein et al. BMC Urology (2018) 18:25 Page 2 of 8

http://www.siu-urology.org/society/national-delegateshttp://www.siu-urology.org/society/national-delegates

regardless of size, and the AFU guidelines differentiatebetween > 20 mm and < 20 mm for all renal stones.Figure 1 shows the consensus decision tree resulting

from semi-automatic comparison of all decision trees.SWL and URS were the most commonly recom-mended procedures for all stone sizes and locations.Moreover, PNL is mentioned as a treatment optionfor all renal calculi by all guidelines except for theAUA and SUA guidelines, which do not recommendit for the treatment of smaller non-lower pole renalcalculi.Comparative analysis assessing the most often recom-

mended combination of procedures revealed an agree-ment ranging from 50 to 83% for different stone sizesand locations (Fig. 2). A high degree of consensus wasfound in particular for lower pole renal stones below20 mm (83% of the guidelines recommend ‘SWL or URSor PNL’) and distal ureteral stones (83% of the guidelinesrecommend ‘SWL or URS’).In contrast, we saw a low level of agreement for the

treatment of proximal ureteral stones. The EAU, AUAand DGU guidelines recommend SWL or URS, whereasthe other 3 guidelines additionally list PNL and open

Table 1 Recommendations of the SIU members represented bydelegates regarding surgical stone treatment

SIU Member Own guideline Reference toother guideline

Language /latest version

Albania No No

Argentina Yes Spanish / 2014

Australia No EAU

Austria No EAU / AUA

Brazil No No

Canada Noa No

China No No

Colombia Nob No

Costa Rica No No

Cuba No No

Cyprus No No

Czech Rep. No EAU

Egypt No EAU / AUA

Finland No No

France Yes French / 2004

Germany Yes German / 2016

Ghana No No

Greece No No

Guyana No No

Haiti No No

Hungary No No

India No No

Indonesia No No

Iran No No

Israel No No

Italy No No

Jamaica No No

Japan Yes Japanese

Jordan No EAU / AUA

Kenya No No

Latvia No No

Liberia No No

Libya No No

Lithuania No No

Malaysia No EAU

Mauritius No No

Morocco No No

Myanmar No No

Netherlands No EAU

Nigeria No No

Norway No No

Pakistan No No

Table 1 Recommendations of the SIU members represented bydelegates regarding surgical stone treatment (Continued)

SIU Member Own guideline Reference toother guideline

Language /latest version

Palestine No No

Peru No No

Portugal No EAU

Puerto Rico No AUA

Romania No No

Russia No No

Serbia No No

Singapore Yes English / 2001

Slovakia No No

South Africa No EAU/AUA

South Korea No No

Sudan No No

Sweden No No

Switzerland No EAU / AUA

Turkey No No

Ukraine No No

United Kingdom Noc EAU

United States Yes AUA

Zimbabwe No NoaNo guidelines for surgical management of renal calculibNo guidelines for surgical management of ureteral calculicGuidelines for renal and ureteric stones in development (anticipatedpublication Feburary 2019)

Zumstein et al. BMC Urology (2018) 18:25 Page 3 of 8

Fig. 1 Consensus tree listing decision criteria and recommended treatments of all guidelines. (Note that URS for proximal ureteral calculi >10 mm involves ante- and retrograde approach in the EAU-Guidelines)

Fig. 2 Mode tree listing the degree of agreement for the most often recommended therapeutic options. (Note that URS for proximal ureteralcalculi > 10 mm involves ante- and retrograde approach in the EAU-Guidelines)

Zumstein et al. BMC Urology (2018) 18:25 Page 4 of 8

surgery, resulting in a 50% consensus for ‘SWL or URS’as the most common recommendation.An intermediate level of agreement was found for the

remaining situations (67% consensus for renal non-lowerpole calculi and lower pole calculi > 20 mm).A separate comparison of the EAU and AUA guide-

lines including all recommended treatment optionsregardless of hierarchical level showed complete consen-sus for the treatment of ureteral calculi (Fig. 3).However, the EAU guidelines provide wider scope fordecision-making regarding the treatment of renal stones,especially for larger non-lower pole calculi, and the useof PNL.All guidelines provide a hierarchical listing of the

recommended therapies for each situation (Table 2). Thebest agreement between the hierarchical recommenda-tions in the six guidelines was found for distal ureteralcalculi.SWL is recommended as first line therapy in all guide-

lines for smaller non-lower pole renal stones (< 20 mm),whilst only the AFU guidelines recommend SWL as firstchoice for > 20 mm calculi. The situation for PNL innon-lower pole and lower pole calculi is different: forsmall calculi < 10 mm, PNL is first choice in onlythe SUA guidelines, whereas for larger renal calculi> 20 mm, PNL is listed in all guidelines as first-linetherapy.Regarding proximal ureteral calculi < 10 mm, SWL is

first-line therapy in all guidelines except those of theAUA, where URS is recommended as first line and SWLas second line. PNL is not recommended in this situ-ation except for by the AFU and SUA guidelines.

URS is recommended as first line for all distal ureteralcalculi, regardless of size.

DiscussionIf surgical treatment of ureteral or renal stones is indi-cated, clinicians face the challenge of choosing the mostappropriate treatment for each patient. In ambiguoussituations, evidence-based guidelines can help the urolo-gist with decision-making.Our systematic search covering all members of the

SIU showed that the EAU and AUA guidelines are themost frequently referenced guidelines worldwide for thetreatment of urolithiasis. Treatment recommendationsare based on stone size and location in all availableguidelines. Remarkably, the websites of most nationalurological associations neither refer to a reference guide-line nor provide their own guidelines. However, effortsare made to improve this situation such as those by theBritish Association of Urological Surgeons (BAUS) incollaboration with the National Institute for Health andCare Excellence (NICE). Besides a linked guideline onlaparoscopic stone removal, new guidelines covering themanagement of renal and ureteric calculi are supposedto be published by February 2019 (https://www.nice.or-g.uk/guidance/conditions-and-diseases/kidney-conditions/renal-stones). We suggest that urological associationswithout own guidelines should refer to one of the citedguidelines to provide a reliable source their memberscan refer to.Regarding location – except for the AFU guidelines

[14] – all guidelines consider calculi in the lower renalpole separately because of a reduced possibility of

Fig. 3 Comparison of the decision trees of EAU and AUA guidelines. Note that URS for proximal ureteral calculi > 10 mm involves ante- andretrograde approach in EAU-Guidelines

Zumstein et al. BMC Urology (2018) 18:25 Page 5 of 8

https://www.nice.org.uk/guidance/conditions-and-diseases/kidney-conditions/renal-stoneshttps://www.nice.org.uk/guidance/conditions-and-diseases/kidney-conditions/renal-stoneshttps://www.nice.org.uk/guidance/conditions-and-diseases/kidney-conditions/renal-stones

passage of fragments [15, 17–20]. Most guidelinescategorize stone size into < 10 mm, 10–20 mm, and >20 mm. However, the AUA guidelines for renal calculionly differentiate between ≤10 mm and > 10 mm forlower-pole stones and between ≤20 mm and > 20 mmfor non-lower pole stones [1, 3]. There is also somedeviation from the most common classifications in theAFU guidelines [14], SAU guidelines [11, 12], and SUAguidelines [16].Surgical treatment of ureteral calculi depends on stone

location and size. The AUA guidelines state that earlierclassifications split the ureter into thirds and that thiswas because of the surgical approaches available. Now-adays, the ureter is divided into two sections marked bythe crossing of the iliac vessels. All guidelines use a cut--off level of 10 mm to define the surgical approach.Concerning hierarchical recommendations, all guide-

lines give treatment options in multiple scenarios, listedas equal or, in some cases, as first-, second- or third-linesurgical treatment. To prevent the loss of recommendedsecond- or third-line surgical therapies in our compara-tive analysis, we included all surgical procedures pro-posed as “standard procedures”, regardless of theirhierarchical position in the guideline text.Our consensus tree showed a high degree of consensus

for most recommended procedures in nearly all ureteraland renal stone scenarios. We did, however, detect some

significant differences, mainly concerned with the ratingof SWL, where little consensus between guidelines forlarger renal, distal ureteral and small proximal ureteralcalculi was found. One reason for that might be geo-graphical discrepancies in the technical performance ofinterventions, such as the strict use of X-ray-localisationsystems for SWL in the United States compared to thewidely available ultrasound guidance in Europe. Consid-ering the rapid technological improvements of URS andPNL, further evidence seems to be required here.While the mode tree showed a high degree of agree-

ment for lower pole renal stones of < 10 mm and10–20 mm and distal ureteral stones, a low level ofagreement was found for proximal ureteral stones. Thiscan be explained by the AFU and SUA guidelines alsorecommending PNL for proximal ureteral stones, andthe SAU guidelines also recommending open surgery.However, the reason for this might be rather missingupdates of some guidelines in the recent past, than a reallack of evidence for these scenarios. Thus, the last revi-sions of the SUA [16] and AFU guidelines [14] wereissued in 2001 and 2004 and do not, therefore, reflectthe latest developments.All other guidelines clearly focus on SWL and URS

in such cases. However, at this point it must be men-tioned, that EAU guidelines consider a percutaneousapproach for proximal ureteral calculi under the term

Table 2 Hierarchical levels of the most commonly recommended therapies (SWL, URS, PNL) in different guidelines

S SWL, U URS, P PNL, E Evidence declaration with GR Grade of recommendation in EAU, LE Level of evidence in AUA, Degree of Panel consensus in DGU

Zumstein et al. BMC Urology (2018) 18:25 Page 6 of 8

“antegrade URS” and state that percutaneous ante-grade removal of ureteral stones should be consideredin selected cases [2].The comparison of the EAU and AUA guidelines as

the most commonly cited guidelines worldwide revealedseveral discrepancies. In general, the EAU guidelines givemore therapeutic options for specific situations, delegat-ing the choice of the appropriate treatment to the urolo-gist and patient’s preference.Since several approaches may be appropriate in spe-

cific situations, guidelines also rate procedures hierarch-ically in such cases. Our analysis of these hierarchicallistings revealed a number of discrepancies betweenguidelines, showing that for the choice between SWLand URS, available data might have been interpreteddifferently. While the AUA guidelines refer to anunpublished systematic review conducted by theguidelines-panel [1], the EAU guidelines recommenda-tion is based on a meta-analysis [18] and a work carriedout by Hong et al. [19].Moreover, PNL is mentioned as a treatment option for

all renal calculi by all guidelines, except for the AUAand SUA guidelines, which do not recommend it for thetreatment of smaller non-lower pole renal calculi.Although recent developments in minimal invasive PNLtechniques are mentioned in the EAU and AUA guide-lines, these procedures are not yet listed separately inthe recommendations. The comparison of recentadvances in PNL is particularly difficult because differentapproaches are associated with substantially differentdegrees of invasiveness and technical complexity.SWL still plays an important role in all guidelines.

This is remarkable because several recent studies haveshown that technical advances with URS achieved higherstone-free rates and had fewer complications than previ-ously [21, 22]. However, lower morbidity and economicaspects [2, 23, 24] support the use of SWL, and thisexplains its continuing prominence in all guidelines. Afurther explanation is that, based on the publisheddecision tree and consensus tree, the EAU guidelinesstate that more than 90% of renal and ureteral calculimight be suitable for SWL according to the recentliterature [25–27].One limitation of our study was disregarding hierarch-

ical recommendations when comparing recommendedapproaches. Since comparing decision trees with mul-tiple weighted recommendations would have resulted inan exuberant consensus tree, we decided to include allrecommended therapies for each specific situation andweight them equally to avoid distortion of the compara-tive analysis through oversimplification. To compensatefor this, hierarchical recommendations of different treat-ment options were analysed separately in our compara-tive analysis (Table 2). Guideline language is usually

restricted to the nation’s main language. Due to linguis-tic difficulties caused by different font systems or scripts,some national guidelines could not be included in ouranalysis (e.g. the guidelines of the Japanese UrologyAssociation) or might have remained unnoticed. More-over, our systematic analysis excluded stone compos-ition, postoperative management, follow-up and specificsituations such as staghorn calculi, urolithiasis in preg-nancy or in children. Techniques such as laparoscopicand open surgery are part of many guidelines (e.g. SAU,AFU, EAU and AUA). While these approaches are partof the standard treatment recommendations in SAU andAFU guidelines, EAU and AUA guidelines mention theuse of these approaches in limited special scenarios only,which is why we did not include the latter in ourcomparative analysis. Of course, these aspects must beadditionally considered in decision-making.

ConclusionSix guidelines with recommendations for the surgicaltreatment of urolithiasis to support urologists in decision-making were available for inclusion in our analysis. Whilethere is generally a high grade of consensus for most stonescenarios, we also detected some relevant discrepanciesbetween different guidelines. In particular, lower consen-sus was found for the treatment of proximal ureteralstones and hierarchical levels of recommended treatmentsfor specific situations. These are, however, controversialsituations where adequate evidence to assist withdecision-making has yet to be elicited by further research.

AcknowledgementsNot applicable

FundingNone

Availability of data and materialsThe datasets used in the study can be found in the cited guidelines.Analyses are available from the corresponding author upon request.

Authors’ contributionsVZ contributed in project development, data collection, data analysis andmanuscript writing. PB contributed in project development, data collection,data analysis and manuscript writing. DA contributed in projectdevelopment, data analysis and manuscript writing. HPS contributed inproject development, data collection and data analysis and manuscriptwriting. CP contributed in project development, data collection, data analysisand manuscript writing. PMP contributed in project development, datacollection, data analysis and manuscript writing. All authors read andapproved the final manuscript.

Ethics approval and consent to participateNot applicable

Consent for publicationNot applicable

Competing interestsThe authors declare that they have no competing interests.

Zumstein et al. BMC Urology (2018) 18:25 Page 7 of 8

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.

Author details1Department of Urology, Cantonal Hospital St. Gallen, St. Gallen, Switzerland.2Department of Urology, University Medical Center Hamburg-Eppendorf,Hamburg, Germany. 3Department of Radiation Oncology, Cantonal HospitalSt. Gallen, St. Gallen, Switzerland. 4Department of Radiation Oncology,lnselspital, Bern University Hospital, Bern, Switzerland.

Received: 22 March 2017 Accepted: 8 March 2018

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